On Woodstock Sessions, Vol. 2, the first collaborative album from funk-jazz group Medeski Martin & Wood—keyboardist John Medeski, bassist Chris Wood, drummer Billy Martin—and Wilco guitarist Nels Cline, Cline plays it dangerous. This is not a “sit-in,” really—the vibe is more like he’s a full member of a slightly different band. Over nine tracks of improvised noisefunk, Cline is never timid or careful; he’s an equal, standing his ground. The results are intense and creative. The quartet shines especially bright during a pair of grooves that spring up seemingly from out of nowhere. During “Arm & Leg,” Martin initiates a soulful, hip-hop-influenced slow jam. And about five-and-a-half minutes into “Les Blank,” thick bass, enthusiastic drums, celebratory organ and sly guitar-riffing amount to a joyful juncture. There are moments of peace, too. The first four minutes of “Les Blank” are filled with soothing weirdness. And “Cinders” is a work of psychedelic serenity.